Spark-plug.



J`.'L.'DO'NAT.

SPARK PQUG. APPLICATION mfp JUME'M. 1917.

Patented Jar-1.11919.

f UNIT-EI) -isTAi-fns rariiiai"v onFIoE.

JosErHI.. DONAT, or CHICAGO, ILLINOIS.

Application led I une 14,

To all whom z' may concern.' y

Be it known that I, Josiirn L. Doxn'i, a citizen of the United States, residing at Chicago, in the county of Cook and State of` Illinois, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a specification.

invention relates to improvements in Spark plugs.

The primary object ofqinyjinvention is to provide a sparkv plugwhichy,willproduce a magnetic field attli terin/inal'jend. of.: tie/' central conductor'/wltreb, 'tof/enl/arge/ginch pushout, or projecit'f,tlie spail,ft'pfffodiioea" larger, stronger and .more ytlfti'rnig,charge-i igniting flame with a giv` currentf. l i' Another. object of my invJei'itiQf1.\` is' to reinforce and strengthen the relativelypre'fraycas porcelain, or the like, by embeddingginoie or less of the central conductorl`-thereiii`,"

molding the porcelain around Another object of my inventionagrA vide' means, in the, central `conductipii,,suoli,"

as a spiral portion thereof,`i. where'bft,",t-he proximity of the sparking electrodes may be varied by elongating or contracting` spiral. `\.\\\\v Other, further and more specific objects\.\liolding nut Q3 of my` invention will be readily understood, by persons skilled in the art, from al consideration of theV following description when vtaken in conjunction with the drawings,

wherein z-f Figure 1 is a'central vertical section of my preferred form of spark plug.

Fig. 2 is a similar View' of a modiiication.-

Fig. 3 is a. cross section, taken on line 3-3 of Fig. l.

In all the views the saine reference characters are employed to indicate similar parts.

-In the embodiment. illustrated in the aecoinpanying drawings, 5 is a plug body,

threaded 'as at 6, for insertion in the cylin-.

' as usual vin such structures. 55

der head of an engine. 7 '1s an insulating body of porcelain, or the like, provided with a shoulder 8, foi-.insertion in the larger upper portion'of the plug body, and 9 is a more or less, yieldable Washer, upon which the' enlarged portion 8 ofthe porcelain .structure is seated and 10 is a similar washer under the screw threadedbushing 11. Between these washers the porcelain body 7 is held in place,

lThe central conductor, of theplug'lQ, is I SPARK-'moa Specification of Letters Patent.

i917. sei-iainofimfii.

preferably spiral in forin` terminating in an enlarged, axially extending threaded part- 13 for the wire ,clampingnut lf-t. AThe helical portion of the 'central conductor terminates in an axially extending terminal 15, for cooperation with the terminal or elecftrodedpy that is connected to the body part the plug 5.x .letween the terminals 15 and 1li`tliespa`rk. is produced. The inodilied"forin shown in Fig.

tliins substantially the saine parts in the ',syai'ne i'jella/tli/nsand which are indicated with fjth/gani/e/refereiice characters with addition "',of the exponent p'riine but in thisl foign of the structure the spiral 17 of the central conductor 12, extends to a shoulder 18 formed luy-"conjunction of they two coaxial 'perforations in the porcelain body part v7.

, sf toryinsulating body of tl`ie\str\ucture. such ,llhe axially-extending enlarged threaded `stein 13`\is somewhat. longer than the one -`shoivnin Fig. land passes freely through iiaxiallyextending perforation 20 inade in ,the,porcelain'body-7.` A concentric b ut Vlarger perforation 21 is inade in the lower poi/'tion of/the porcelain. to accommodate the y. ppiral 17. 1n Fig. 2 the central conductor imay -be bodily removed from the porcelain ybody T by disengaging and removing the Italia "llli`e"el v`c,tric current passing through the central conductor will pass over the lower portion thereof in spiral forni, producing a magnetic field in the neighborhood of the terminals 1li-land 1G, thereby causing the spark to be projected from the electrodes -15 and .16 `in a superticially larger or more extensive body, 'thereby providing a greater igniting surface for the explosive charge, and extending farther into the charge, as the yresult of its magnetic projection. There is .more or less self induction produced by the spiral of the central conductor, which has -the effect to prolong the duration of the Spal-k, to some extent, thereby increasing the etliciency of the plug structure.

' The central conductor 12 of the structure. shown in Fig. 2 may be bodily removed land anotherl structure of similar character placedin its stead. In Fig. 1, however, the central conductor 12 is immovably associat- 2 ron- A and thevire clamping' Patented Jan. 1919.

ed with the surrounding porcelain insulating one modification, it is manifest that other modifications may be made, Within the scope of the appended claim.

Having described my invention, what I claim is z- A spark plug comprising. an insulating body having an axial bore of two diameters,

the larger bore being in the lower end of said body; a shoulder formed by the oon- 10 junction` of said bores; a, central'conductor,

comprising a larger, straight portion for inclusion in the smaller bore and a spirally Wound portion, of smallerdiameter, for in- 'clusion inthe larger bore, the free terminal end of the spiral forming one 'electrode of l5 the spark gap and a shell having a coperating electrode.

In testimony lwhereof I hereunto set my hand.

.JOSEPH L. DONAT. 

